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Post Calibration Radiation Inspection (Radiographic)
About The Post Calibration Radiation Inspection (PCRI) is an inspection record for conventional radiography that details the step-by-step inspections and examinations prepared by trained agencies on the serviceability, quality assurance and control, as well as the functionality and operation of these ionizing radiation devices onto a document that complies with mandatory Federal, State, and Local Laws, Regulations & Performance Standards. The following PCRI is a mandatory requirement to be performed after new installations and repairs as well as during routine annual calibrations and safety inspections. System Identification The system identification or equipment identification is the medical devices and its system components including the master control, room control, radiographic tube head's make and model, manufacturer name, and the device serial number used for FDA tracking and QA documentation. Additionally, we will input the systems highest kVp and mA that can be selected on dial and displayed on the the master control. Visual inspection Visual Inspection, used in maintenance of medical equipment, means inspection of equipment and structures using all of the human senses such as vision, hearing, touch and smell and/or any non-specialized inspection equipment to include tape measures and/or magnetic angle measuring tool to verify proper operation. The following are some common verification inspections for general radiologic devices: Pass or fail * CERTIFICATION LABELS ARE AFFIXED AND VISIBLE * STEEL COUNTERWEIGHT CABLES (Ensure cables are clean and free from dust and other debris) * SHOCK-PROOF HIGH TENSION CABLES * TUBE HANGER ASSEMBLY AND YOKES * INDICATOR LIGHTS * X-RAY TUBES FOR OIL LEAKS * INTERLOCKS (Door and table interlocks shall forbid exposure when in the open position. This includes the fluoroscopic primary barrier, which shall be in position for use in order for fluoroscopic exposure to be possible.) * LOCKS and EXPOSURE SWITCHES (At exposure times of 0.5 sec or more the switch must terminate the exposure if manual pressure is removed.) * VIEW BOXES (The brightness of the view boxes used to check films after processing shall be within 15% of the brightness of the view boxes used by the radiologists to read the films.) * LEAD APRONS, GLOVES, AND DRAPES (Protective garments and drapes shall not have tears, which impair their radiation protection function.) * BACKUP SAFETY TIMERS * TABLE AND TUBE STAND MOTION * BEAM LIMITING DEVICES (Manual and automatic mode) * TABLE ANGULATION LIMIT SWITCHES (Record angle in degrees using a magnetic angle measuring tool) * DOES TUBE OVERLOAD PROTECTION CIRCUIT DISABLE EXPOSURE CIRCUIT? * IS THE PRODUCTION OF X-RAYS INHIBITED UNTIL ANODE IS UP TO SPEED? * DOES BRAKE ON HIGH SPEED STATOR OPERATE CORRECTLY? (Record coast down time for anode after exposure Three/Single Phase Voltage/Line Drop (WARNING: LETHAL VOLTAGES PRESENT) The Three or Single Phase Voltage or Line Drop is a power quality test of the incoming power to the x-ray device and its components. If power coming into the machine is dirty then there can be no proper alignments to adjustments made. Test Frequency Annually Test Tools A Digital Multimeter with VAC mode Procedures No Load A Digital Multimeter (DMM) will be used to measure the incoming power (in VAC)from the circuit breaker panel. This is called the no load test. You will measure multiple test spots marked "L1" (red lead) to the metal case (black lead goes to Ground). Next, you will proceed to measure "L3" (red lead) to ground (black lead) and finally L1 (red lead) to L3 (black lead). Record all of the following measurements taken. Load A Digital Multimeter (DMM) will be used to measure the incoming power (in VAC) from the circuit breaker panel while an x-ray is being taken at 90 kvP and 250 mA. This is called the load test. You will measure a single test spot marked "L1" (red lead) to "L3" (black lead) under an x-ray shot. The voltage drop will be quick so watch carefully. Record the following measurement taken. Finally, the percentage drop should be less than 10%. Exposure Timer Accuracy The Exposure Timer directly affects the total quantity of radiation emitted from the tube an accurate exposure timer is critical for properly exposed radiographs and reasonable doses. Using an X-ray Quality Assurance meter such as RTIs Piranha you will measure multiple x-ray timing settings. On the QA meter display the measurements will be displayed in milliseconds (msec). Normally, the tolerance is within +/-5 milliseconds or the x-ray devices OEM listed tolerance. Radiograpghic Leakage Reproducibility Beam Quality SID Detent / Scale Accuracy Illumination Light Field Offset Light Field / X-ray Field Alignment The Light Field and X-ray Field Alignment (Field Size Versus Indicators) is a two part test: 1). x-ray and light field congruence (how far off is the center of the radiation field to the center of the light field) and 2). x-ray/light field size (are they the same size). The light field is supposed to represent the area that is supposed to be irradiated by the x-ray beam. In a perfect world, this means that the center of the light field and x-ray field should match. Because of how the light field is projected, this can be affected by the position of the light bulb, the type of light bulb and the position or angle of the mirror. In the US, the x-ray and light field alignment needs to be within 2% of the SID (2 cm for a 40"/101.8 cm). The other part of the test checks whether the size of the light field is the same as the size of the radiation field produced. If you set the collimators to produce a 24 x 30 cm light field, the radiation field produced should also be 24 x 30 cm. In the US, the difference between the length/width of the light field and the radiation field needs to be less than 2% SID, and the sum of the length and width differences needs to be less than 4% SID. Test Frequency Annually SID 40” Technique Factors 60 kVp, 5 mAs Test Tools An 8”x10” cassette (or similar size) and 8 pennies Procedures 1. Place the 8" x 10" film cassette in the x-ray bucky. 2. Center the light field to the center of the cassette at a 40” SID. 3. Collimate the light field beam to approximately a 5” x 7” beam. 4. Mark the four sides of the light field. One method is to place two pennies together with medical tape so that the two pennies touch. Place the center of the two pennies at the edge of the light field. Do this on each of the four sides. Facing the film, place a penny or marker in the light field to identify the lower right corner of the film. 5. Expose and develop (process) the film. 6. Examine each of the four sides of the exposed film. The inside pennies closest to the center of the light field shall lie partially or completely in the radiation light field. The outside pennies may partially lie in the exposed field but no outside penny can be fully covered by the radiation field or exposed field offset. 7. Misalignment in either dimension (horizontal misalignment is the sum of the deviation of the right and left edges, while vertical misalignment is the sum of the top and bottom edges) cannot exceed 0.8 inches. The deviations should be less than +/- 1/2 the diameter of the penny at any edge and must be less than +/- the diameter of the penny. In other words, the outside pennies should never be covered by the exposed field offset otherwise contact your OEM service engineer. X-ray Field/Image Receptor Alignment The Light Field and X-ray Field Alignment (Field Size Versus Receptor Offset) The alignment of the light field is designed to define and verify the outline of the X-ray field exposure. In the plane of the image receptor, the misalignment, of the edges of the visually defined light field with the edges of the X-ray exposed field must not exceed 2% of the focal spot to image receptor distance. Test Frequency Annually SID 40” Technique Factors 70 kVp, 10 mAs Test Tools An 8”x10” cassette (or similar size), a ruler (in inches) Procedures 1. Place an 8" x 10" cassette in the x-ray bucky and lock into place. 2. Make sure that the x-ray tube is centered to the table. 3. Center the bucky to the collimator centering light. 4. Set x-ray collimator (tube) to 40” SID. 5. Manually collimate the light field to leave a 1" border around the film. (This will leave an unexposed border on the film after processing.) 6. Expose and process the film. 7. To find the center of the light field film, place a ruler at opposite corners of the 8 x 10 light field on film and draw a line. The point where the two lines cross is the center of the light field on film. Because film has rounded edges, some estimating will have to be done when positioning the ruler in opposite corners. 8. To find the center of the exposed field of the film, place the ruler at opposite corners of the exposed portion of the film and draw a line. The point where the two lines cross is the center of the exposed field. 9. Measure the distance between the center point of the light field and the center point of the exposed field. 10. Record this information. As a rule of thumb, the center of the field light to the center of the exposed film should be less than 2 cm (or 2%) ''Compare the result to the acceptance limit previously identified. At a 40” SID, the maximum acceptable misalignment would be 0.8 inches. '' Field Sizing (PBL) The Field Sizing Positive Beam Limitation (PBL) is how the collimator automatically adjusts to an exact cassette size once the cassette is placed in the bucky. The x-ray beam shall not differ from the image receptor size by more than 3% of the SID in any one dimension or a total of 4% of the SID in both dimensions. Test Frequency Annually SID 40” Technique Factors 70 kVp, 10 mAs Test Tools An 8”x 10” cassette (small size), a 14" x 17" cassette (large size), and a ruler (in inches) Procedures 1. Place an empty, 8" x 10" (small) cassette in the bucky. 2. Check that the collimator is in the automatic mode. 3. Set the SID to 40” and lock in place. 4. Place a loaded, 14" x 17" (large) cassette on top of the table. Center the tube to the table, rotate the x-ray tube to 90 degrees so the x-ray tube is perpendicular to the large cassette. Activate the light field and center the x-ray tube to the bucky. Make sure that the large cassette on the tabletop is centered as well. 5. Make an exposure and process the film from the large cassette. 6. If the exposed field size from the larger cassette does not exceed the actual film size in the bucky, then the PBL system meets requirements. If the exposed field size from the larger cassette exceeds the actual film size for the cassette in the bucky, then triangulation utilizing the exposed film from the large cassette must be done to determine the actual field size at the bucky. 7. Measure the exposed field Width from left to right and record 8". 8. Measure the exposed field Length at near from top to bottom and record 10". 9. Record this information. As a rule of thumb, the allowable tolerance at 40" SID is less than 1.6 cm and at 72" SID is less than 2.88 cm (or 4%) Tube Current Output and Linearity Entrance Skin Exposure ESE is the measurement of radiation output at the point of skin entry for common X-ray examinations, including fluoroscopic and conventional radiology. Traditionally, we must compare the facility’s entrance skin exposure for chest, abdomen and LS spine examinations to that obtained during the Annual Medical Physicist’s Radiographic QC Survey. These units are measured in milli Roentgen (mR). Test Frequency Annually SID 40” Technique Factors 70 kVp, 32 mAs Test Tools A X-ray Quality Assurance meter (e.g. RTIs Piranha or Barracuda) Procedures 1. Place an empty, 8" x 10" (small) cassette in the bucky. 2. Check that the collimator is in the automatic mode. 3. Set the SID to 40” and lock in place. 4. Place a loaded, 14" x 17" (large) cassette on top of the table. Center the tube to the table, rotate the x-ray tube to 90 degrees so the x-ray tube is perpendicular to the large cassette. Activate the light field and center the x-ray tube to the bucky. Make sure that the large cassette on the tabletop is centered as well. Kilovoltage Verification MilliAmperage Verification Action Required References Links *Safety Code 35 Summary Quality Control Procedures Radiography/CR/DR